Definition of trio sonata in English:

noun

Only in the Baroque trio sonata did it have no place, for then the continuo provided the middle harmony.

The famous Adagio is based upon a tiny fragment of manuscript - a mere six bars of melody and bass line; all that remain today of the slow movement of a trio sonata in Albinoni's own hand.

The trio sonata for flute and strings is the work's centrepiece, clearly meant for Frederick to play, but it is in the form of a sonata da chiesa (church sonata), and in Frederick's vast music library, there was not a single sonata da chiesa.